Gas distributor head



Sept. 16, 1958 A. v. ALEXEFF GAS DISTRIBUIOR HEAD Filed April 22, 1955 FIG. I (PRIOR ART) (PRlOR ART) FIG, 2 (PRIOR ART) FIG. 3

FIG. 4

Fl G 9 INVENTOR.

ALEXANDER V. ALEXEFF WIDTH 0F WEB ATTORNEYS United States Patent GAS DISTRIBUTOR HEAD 'Alexander V. Alexetf, Cleveland, Ohio, assignor to Industrial Ovens, Incorporated, Cleveland, Ohio, a corporation of Ohio The present invention relates to apparatus for treating the width of a passing web with a. gas, such as air, and more particularly to a gas-distributing head for evenly distributing the gas over the surface of the web.

it has been a common practice in manufacturing many types of web material to heat, cool, dry or otherwise process the web by passing it through one or successive blasts of air or other gas projected at the web by one or more distributing heads extending across the width of the web, one end of each distributing head being connected to a gas supply. In some applications, as many as forty or fifty such heads may be employed. The heads should ideally cause the gas to impinge at a uniform velocity across the entire width of the web. With such even impingement, the web receives uniform treatment, and minimum equipment cost is involved in assuring that the necessary degree of treatment is achieved on all portions of the web surface. However, to date, the art has been unable to provide a distributor structure which is at once effective in accomplishing even distribution and practical from the standpoint of cost and elaborateness of the equalizing means. it may be attempted to accomplish this object by progressively narrowing the nozzle or slot through which the gas, such as air, is expressed from the distributor. While this tends to even mass flow along the length of the distributor, it does not avoid, and in fact may tend to exaggerate, the condition of varying gas velocities along the length of the distributor, so that the passing web is subjected to widely variant treatment across its width.

The general object of the present invention is to provide a distributor which is both extremely simple in structure and highly effective in creating a uniform curtain of moving air or other gas.

Another object of the invention is to provide a simple means for passing progressively smaller volumes of gas across the width of the distributor structure as the velocity tends to increase across this width, and providing an additional extremely simple means extending across the width of the distributor to allow a degree of gas expansion which increases as the velocity tends to increase across the width, such expansion lowering the velocity and increasing the volume (decreasing the density) of the passed gas to a progressively increasing extent across the width of the distributor head to provide output gas of uniform velocity and density across the distributor head.

The above objects are attained through the provision of a nozzle slot which may not vary in dimensions along its length but which along its length is increasingly dampered at its input side, the nozzle thus serving at advanced points along its length as an expansion chamber, the degree of expansion varying inversely to the degree of damping.

The objects and advantages of the invention will be more clearly understood from the following description of a specific example of the invention.

Patented. Sept. 16, 1958 In the drawings,

Figure 1 is a side view of one typical form of conventional distributor.

Figure 2 is a side view of another distributor which does not embody the invention. I

Figure 3 is a side view of a distributor embodying the invention.

Figure 4 is a side view of another distributor embodying the invention.

Figures 5-8 are, respectively, views taken in crosssection on line 5-5 in Figure 1, 66 in Figure 2, 7-7 in Figure 3 and 88 in Figure 4.

Figure 9 is a graphic indication of velocity distribution across a web located a. short distance from the nozzle slots of the several distributor structures discussed below.

In Figures 1-8, the diameters of the distributors are exaggerated for purposes of clarity, that is, the distributors are foreshortened. In an actual installation, the length of a distributor typically would be in the vicinity of eight or ten times its large diameter.

Shown in Figure 1 is a distributor of a type known to the art. A gas, commonly air, is supplied through a line 11). The air is received within the distributor body 11 and is expressed out the nozzle slot or path-of-flow defined by the flanges or guide members 12, the end of thebody 11 opposite to the line 10 being closed. The air is directed toward a passing web, and the parts are arranged so that the nozzle slot extends across thewidth of the web and usually a small distance past both edges of the web. in ya typical installation, the web might be 62 inches wide and the nozzle slot might be.70. inches wide, with the web spaced less than 12 inches from thenozzle slot. t

With the above arrangement, output velocities are considerably higher toward the outer end of the distributorand toward the outer edge of the-web, as indicated by curve, 1, in Figure ,9. The progressively reduced crosssection of the distributor body 10, however, does represent some improvement over a cylindrical distributor of conventional type (not shown) .which is similar in'all respects to the distributor shown in Figure 1, except that the distributor body is cylindrical rather than tapered. The velocity distribution provided by such a cylindrical distributor is indicated by curve 0 in Figure 9.

Shown in Figure 2 is a distributor having a supply line 20, distributor body 21 and tapered nozzle slot or pathof-flow defined by the flanges or guide members 22. As indicated by curve 2 in Figure 9, this arrangement does not eliminate the wide disparity in discharge velocity across the width of the web.

Shown in Figure 3 is a distributor embodying the invention. The supply line 30 supplies air to the distributor body 31 from which the air is expressed through the nozzle slot or path-cf-flow defined by the flanges or guide members 32. Extending along the input side of the nozzle slot is a damper 33 which is positioned for progressively greater damping along the length of the distributor. Through such progressively greater damping at the input side of the nozzle slot, a remarkable degree of uniformity of velocity distribution may be obtained across the width of the web being treated, as indicated by curve 4 in Figure 9. Further, the mass of distributed air is constant or very nearly constant across the width of the web. The mass flow of air or gas entering the nozzle slot from points toward the outer end of the distributor is reduced by the damper, and the normally higher velocity of this air or gas is then reduced by expansion within the nozzle slot which is wide compared to the damper opening. This effect is progressively more pronounced with the greater damping along the length of the nozzle slot, and the .net effect is a balancing out of flow 3 conditions so that -air-'or gas at uniform velocity (and density) .is directed toward the --web.

These highly advantageous aeffects are disturbed very little by the substitution of a cylindrical distributor body for the tapered distributor body 31 of Figure 3. Thus, in Figurelyasupply line 40 supplies air to a distributor body 41 from which the air is expressed through the nozzle slot or path-of flow definedby the flanges or guide members 42 along which slotextehdsthe-input damper 43. The velocitydistribution attained by such a structure is indicated by curve 4 in Figure 9. Such results are quite comparableto those indicated by curve -3 in Figure 9.

Obviously, distributors embodying the invention may be -varied'in many respects from'the somewhat schematic showings of Figures 3 and 4. 'For example, the distributor body may have a cross-section which is polygonal rather than-circular. A plurality of nozzle slots maybe provided. The outlet aperture from the distributor body may comprise'a series of holes rather than a continuous slot. it is particularly desirable that the damper be adjustable. To this'e,nd,the distributor shown in Figure 4 maybe provided with slots 44 in which are adjustably received-damper bolts 45 in a manner which will .be apparent from the drawings.

'From the point of view of fabrication, it is highly desirable. thatthe-nozzle slot be of constant width along its length, but it is to benote'd that variations in this width can be compensated for in significant measure by corresponding variations in damper aperture.

The immediately preceding observations should make it apparent thatthe invention is not limited to any precise form of distributor or to other details which are merely incidental to the above disclosure. The scope of the inventionis defined in the following claims.

What is. claimed is:

1. A distributor for producing a curtain of gas comprising :a relatively long and narrow hollow body adapted to -be:.'connected to a gas supply-line at one end and closed at-theptherend, exhaust aperture means extending along the length of said'body on at least one side thereof, said aperture means communicating with the interior of said body, SfidTZIPEIflll' means also communicating with the exterior atmosphere through a path-of-flow dcfined'by 'and enclosing the outflow side -of said aperture means,

damper means at least partly defining said aperture means, said damper means and guide members being so proportioned and positioned that said aperture means presents a smaller cross-section to exhaust flow than does the extent of said path-of-flow at a majority of locations along the length of said body, and the ratio of crosssection presented to exhaust flow by said aperture means on the one handto minimum cross-section presented to exhaust flow by said path-of-fiow on the other hand is smaller toward said other end of said hollow body than it is near said one end of said hollow body.

2. A distributor for producing a curtain of gas comprising a relativelylong and'narrow hollow body adapted to be connected to a gas supply line at one end and closed at the other end, exhaust aperture means extending along the length of said body on at least one side thereof, said aperture means communicating with the interior of said body, said aperture means also communicating with the exterior atmosphere through a path-of-fiow defined by guide members extending along the length of said body and enclosing the outflow side of said aperture means, damper means at least partly defining said aperture means, said damper means and guide members being so-proportioned and positioned that said aperture means presents a smaller cross-section to exhaust flow than does the extent of said path-of-flow at a majority of locations along the length of said body, and the ratio of cross-section presented to exhaust flow by said aperture means on the-one'hand to minimum cross-section presented to exhaust flow by said path-of-fiow on the other hand becomes progressively smaller from said one end to said other end along the length of said hollow body.

References Cited in the file of this patent V UNITED STATES PATENTS 157,256 

